Conventionally, radiography using silver salts to obtain radiation images has been employed but there have also been developed radiographic imaging methods not using silver salts. Thus, for example, an imaging method is disclosed in which radiation that has been transmitted through an object is absorbed by stimulable phosphor, followed by exciting the phosphor with an energy to cause radiation energy accumulated in the stimulable phosphor to radiate in the form of fluorescence, and imaging is achieved by detecting the fluorescence, for example, as disclosed in U.S. Pat. No. 3,859,527. Specifically, there is known a radiation image conversion method in which a panel provided with a stimulable phosphor layer on a support is employed and one of or both of visible and infrared lights are used as an exciting energy.
Further, a radiation image conversion panel using a stimulable phosphor comprised of an alkali halide, such as CsBr as a parent component and activated with Eu, was proposed as a radiation image conversion method using a stimulable phosphor of high luminance, high sensitivity and enhanced sharpness. Specifically, the use of Eu as an activator is contemplated to result in enhanced X-ray conversion efficiency.
A radiation image conversion panel exhibiting further enhanced sharpness has been desired in the analysis of diagnostic images and an attempt was made to enhance sharpness as well as sensitivity by controlling the shape of stimulable phosphor particles as a means for improving sharpness. For example, JP-A No. 2-58000 (hereinafter, the term, “JP-A” refers to an unexamined Japanese Patent Application Publication) proposes a radiation image conversion panel comprising a support having a stimulable phosphor layer of columnar crystals formed by a gas phase deposition process and inclined at a prescribed angle to the direction normal to the support.
However, the foregoing stimulable phosphor layer having a columnar crystal structure results in disorder of the columnar crystal structure at the interface of the support so that exciting semiconductor laser is diffused at the bottom of the columnar crystal structure layer, leading to deteriorated sharpness.
As disclosed in JP-A 2003-50298, there is known a radiation image conversion panel in which a columnar crystal structure comprised of a parent component of a phosphor is formed through electron beam vapor deposition and further thereon, a columnar crystal structure comprised of a parent component of a phosphor and an activator component thereof is formed through electron beam vapor deposition to form a phosphor layer.